Massive Winter Weather System Brings 'Epic' Snowfall to Sierra Nevada

A motorist puts on snow chains near Echo Summit, Calif., on Jan. 3, 2017. The California Department of Water Resources held the first manual snow survey of the season near Phillips Station near Echo Summit on Tuesday. The survey showed the snowpack at 53 percent of normal at the site for this time of year.Rich Pedroncelli / AP

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Several feet of snow were forecast for parts of the West as a vast, record-setting band of winter weather swept across the region, freezing many cities, inundating others with floods and spurring authorities to warn of avalanches.

Winter storm warnings were in effect across much of the western third of the country early Thursday, from California to Colorado and Wyoming, including all of Utah's Salt Lake Valley.

Up to five feet of snow was predicted for the Sierra Mountain range, ahead of another winter storm this weekend that will bring several more feet of snow and raise the flood threat to central California.

One forecaster said parts of the range could see “enormous snow totals” of 10-15 feet or more thanks to a series of "atmospheric rivers" — narrow streams of concentrated moisture in the sky — that are expected to wash over the West into early next week.

Enormous snow totals still modeled: 10-15+feet from warm, very moist series of Atmospheric Rivers down-spouting over Sierra Next 10-days: pic.twitter.com/U1cBfPWIJy

The National Weather Service said "significant flooding" was expected across northern and central parts of the state by the weekend, and it issued a flash flood watch for the California Sierra and foothills all the way through next Monday.

Transportation was chaotic across many states. More than 430 arrivals and departures were canceled or delayed Wednesday at Denver International Airport — and more than 60 flights scheduled for Thursday had already been pre-emptively canceled.

Oregon was hit especially hard. In Otis, in coastal Lincoln County, the 8-year-old daughter of a volunteer firefighter was killed Tuesday night when wind sent a tree crashing into her family's home, the North Lincoln Fire and Rescue District said.

"There's been a great outpouring — from school districts, [the] sheriff's office and everyone else — to get together and see what we can do to handle this," Fire and Rescue Capt. Jim Kusz told NBC station KGW of Portland.

The Santiam Pass on U.S. Highway 20 between Salem and Bend was closed for several hours as state crews cleaned up after two avalanches early Wednesday, the state Transportation Department said.

Meanwhile, the Northwest Avalanche Center, an agency of the U.S. Forest Service, issued a "considerable" avalanche threat alert from the Canadian border through Washington state to just south of Portland, Oregon.

The Northwest Avalanche Center issued a 'considerable' avalanche threat alert from the Canadian border through Washington state to just south of Portland, Oregon.Northwest Avalanche Center

Northern California, where mountain areas were already under as much as 4 feet of snow from December storms, wasn't being spared, either.

Soda Springs, a resort community of 81 people near Donner Pass, reported 2½ feet of new snow Wednesday. And Mount Shasta Ski Park, which got 20 inches of new snow, was forced to close Wednesday as power failed across the park, NBC station KNVN of Chico reported.

Interstate 80 was closed in both directions near Colfax and Truckee as state crews worked to clear numerous accidents Wednesday afternoon. The state Transportation Department said the interstate wouldn't reopen until at least midnight.

In Idaho, snow created such hazardous conditions that schools in Boise, West Ada and Nampa were closed, NBC station KTVB of Boise reported. The NWS in Boise said records had been for snow depth and daily snowfall — "but it is still snowing."

???Records for snow depth and daily snowfall have been set as of 6 pm MST, but it is still snowing. Stay tuned for the official final totals pic.twitter.com/d9Xxunxpln

While the weather is creating a sodden mess, "this is actually really good news for the California drought," said Ari Sarsalari, a meteorologist for The Weather Channel. "Not only are they getting some rain from this storm, but also that snowpack is really piling up on top of the Sierras."